fix(.travisy.yml): sequence commands via && instead of ;
fix(.travisy.yml): sequence commands via && instead of ;

fix #399

fgdorais/lean,avigad/lean,soonhokong/lean-windows,sp3ctum/lean,digama0/lean,dselsam/lean,c-cube/lean,soonhokong/lean,javra/lean,leanprover/lean,soonhokong/lean-osx,fgdorais/lean,fpvandoorn/lean2,htzh/lean,avigad/lean,soonhokong/lean,johoelzl/lean,UlrikBuchholtz/lean,Kha/lean,leanprover/lean,leanprover-community/lean,fgdorais/lean,digama0/lean,soonhokong/lean,sp3ctum/lean,eigengrau/lean,johoelzl/lean,levnach/lean,soonhokong/lean-windows,johoelzl/lean,fgdorais/lean,Kha/lean,fgdorais/lean,levnach/lean,dselsam/lean,digama0/lean,soonhokong/lean-windows,leanprover-community/lean,UlrikBuchholtz/lean,javra/lean,eigengrau/lean,soonhokong/lean,c-cube/lean,soonhokong/lean,rlewis1988/lean,Kha/lean,fpvandoorn/lean2,leodemoura/lean,fpvandoorn/lean2,sp3ctum/lean,sp3ctum/lean,soonhokong/lean-windows,fpvandoorn/lean2,dselsam/lean,javra/lean,htzh/lean,dselsam/lean,avigad/lean,levnach/lean,digama0/lean,javra/lean,rlewis1988/lean,c-cube/lean,digama0/lean,htzh/lean,Kha/lean,soonhokong/lean-windows,fpvandoorn/lean,leanprover/lean,leanprover-community/lean,fgdorais/lean,leodemoura/lean,UlrikBuchholtz/lean,UlrikBuchholtz/lean,fpvandoorn/lean,soonhokong/lean-osx,c-cube/lean,rlewis1988/lean,soonhokong/lean-osx,eigengrau/lean,digama0/lean,fpvandoorn/lean,avigad/lean,johoelzl/lean,Kha/lean,soonhokong/lean-osx,leodemoura/lean,eigengrau/lean,leanprover-community/lean,fpvandoorn/lean2,dselsam/lean,leodemoura/lean,javra/lean,leanprover/lean,dselsam/lean,c-cube/lean,UlrikBuchholtz/lean,soonhokong/lean-osx,fpvandoorn/lean,rlewis1988/lean,rlewis1988/lean,Kha/lean,eigengrau/lean,fpvandoorn/lean,levnach/lean,leanprover-community/lean,levnach/lean,fpvandoorn/lean,leanprover-community/lean,avigad/lean,leodemoura/lean,rlewis1988/lean,avigad/lean,sp3ctum/lean,htzh/lean,leodemoura/lean,htzh/lean,johoelzl/lean,johoelzl/lean,leanprover/lean,leanprover/lean